Models irradiation damage

There is evidence that some compounds found in meat are produced by an interaction between phases. For example, hexyl mercaptan or ethyl butyl disulfide would seem to come from free radicals originating in part in the protein and in part in the lipid portions of the meat. Although the current work has seemingly provided greater insight into the mechanisms of irradiation damage in meat, it has also raised more questions. Further studies will be directed toward relating the effects of irradiation on model systems of fat and protein substances in mixtures to try to clear up some of the questions of phase interactions. 

Hofinger, I., Bahr, H.A., Balke, H., Kirchhoff, G., (1999), Fracture mechanical modelling and damage characterization of functionally graded thermal barrier coatings by means of laser irradiation , Mat. Sci. Forum., 308-311, 450-455. 

Cameron M, Wang LM, Crowley KD, Ewing RC (1992) HRTEM observations on electron irradiation damage in F-apatite. Proc 15tli annual meeting Electron Microscopy Society of America. GW Bailey, J Bentley, JA Small (eds) San Francisco Press, San Francisco, p 378-379 Campisano SU, Coffa S, Raineri V, Priolo F, Rimini E (1993) Mechanisms of amorphization in ion-implanted crystalline silicon. Nucl Instr Meth B80 514-518 Carter G, Nobes MJ (1991) A phenomenological model of ion-induced crystallization and amorphization. J Mater Res 10 2103-2107... 

Figure 9.35 shows a schematic of the process for characterising the early stages of irradiation damage. PA (including PALA), APT and SANS all contribute to the development of understanding, and this information can be used to inform mechanistic models of the damage processes. 

T.J. Williams and D. Ellis, A mechanistically-based model of irradiation damage in low alloy steel submerged arc welds, Effects of Radiation on Materials 20th International Symposium, ASTM STP1405, S.T. Rosinski, et al. (eds), ASTM International, West Conshohocken, PA, 2001, pp. 8-27. 

T.J. Williams, D. Ellis, C.A. English and J. Hyde, A model of irradiation damage in high nickel snbmerged arc welds, International Journal of Pressure Vessels and Piping, 79,2002,649-660. 

The key targets for irradiation damage in the cell are the DNA macromolecules of the genes in the chromosomes, which control the functioning of the cell. According to the well-known Watson-Crick model,... 

This chapter will discuss the macroscopic and microscopic properties of Generation IV reactor materials, and the advances in characterization of irradiation-induced defects and in mesoscale modeling of irradiation damage. The majority of the examples provided are based on ferritic-martensitic (F-M) steels, even though they might not always be primary candidates for Generation IV reactors, but the reported defects and microstmctural features are typical of other irradiated alloys, and F-M steels are used as an illustrative example. In some cases, comparisons will be made to austenitic steels to illustrate how differences in crystal stmcture and alloy composition can cause large differences in radiation response. 

Carell has recently presented the study of a flavin amino acid chimera to model riboflavin in DNA photolyases [68]. This amino acid LI (Fig. 20) was synthesized in an enantiopure fashion by building the alloxazine ring onto the epsilon amine of lysine. This coenzyme chimera was applied to the problem of repairing DNA damage caused by UV irradiation. LI was incorporated into an 21-residue peptide, P-1, possessing the sequence of the DNA-binding domain of the helix-loop-helix transcription factor MyoD. 

Raleigh JA, Blackburn BJ (1978) Substrate conformation in 5 -AMP-utilizing enzymes 8,5 -cyclo-adenosine 5 -monophosphate. Biochem Biophys Res Commun 83 1061-1066 Raleigh JA, Fuciarelli AF (1985) Distribution of damage in irradiated 5 -AMP 8,5 -cyclo-AMP, 8-hy-droxy-AMP, and adenine release. Radiat Res 102 165-175 Raleigh JA, Whitehouse R, Kremers W (1974) Effect of oxygen and nitroaromatic cell radiosensitizers on radiation-induced phosphate release from 3 - and 5 -nucleotides A model for nucleic adds. Radiat Res 59 453-465... 

Nearly all modifications that have been detected on the model level (Chap. 10) are also found in free-radical damaged DNA. Obviously the DNA-bound lesions are much more difficult to detect, and there is an ongoing discussion as to the best procedure of their excision (Chap. 13.2 for a review on the excision and repair of base lesions in vivo see Wallace, 2002). Mechanistic details concerning the formation of the base lesions have been discussed in Chapters 10 and 11, and only some additional information will be given below and in the section on clustered lesions where the phenomenon of tandem lesions, two damaged bases that are formed side by side, is dealt with. The yields of damaged bases formed upon y-irradiation in aqueous solution, as has been determined by the GC-MS/SIM technique, are compiled in Table 12.5. 

Chen T, Greenberg MM (1998) Model studies indicate that copper phenanthroline induces direct strand breaks via (5-elimination of the 2 -deoxyribonolactone intermediate observed in ene-diyne mediated DNA damage. J Am Chem Soc 120 3815-3816 Chen T, Cook GP, Koppisch AT, Greenberg MM (2000) Investigation of the origin of the sequence selectivity for the 5-halo-2 -deoxyuridine sensitization of DNA to damage by UV-irradiation. J Am Chem Soc 122 3861-3866... 

Close DM (1999) Where are the sugar radicals in irradiated DNA Radiat Res 147 663-673 Close DM (2003) Model calculations of radiation induced damage in DNA constituents using density functional theory. In Leszczynski J (ed) Computational chemistry, reviews of current trends, Vol. 8. World Scentific, Singapore, pp 209-247... 

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